The efficient use of space for storage of material is a common problem. In many instances the storage space is enclosed, with access available from one end only. Common examples include the interior of a container as used for shipping or road transport, and the interior of a truck or trailer unit with an enclosed canopy.
Another example is in a warehouse where access to an elongated space may be limited to one end only, typically an aisle.
In such cases the goods to be stored must be loaded and unloaded from one end of the available space, and moved into position inside the space. Given this arrangement, the challenge is to find a way of making efficient use of the available space while maintaining the ability to load and unload efficiently.
Normally loading material onto the floor or base of the available space is relatively straight forward. However in many instances the height to which material can be stored on the floor is considerably less than the height available.
This is illustrated by the common situation where material to be transported is loaded onto pallets. These pallets are produced in a standard form, with typical dimensions of 1 meter by 1.2 meters. The pallet is loaded in such a way as to make a stable load which can be manoeuvred readily by means of a forklift or other mechanical lifting device, such as a pallet mover.
The height of the stored material on the pallet will depend on such things as the shape, size, and weight of the stored material.
In many cases the height of the loaded pallet is less than half the height available inside the storage space. Generally it is not appropriate to stack a second layer of pallets directly on top of the material on the lower pallets.
In order to make use of the available space a further floor or support level is required.
However, a permanent second floor or support level is not appropriate for storage spaces where versatility is required to accommodate variations in the size, and particularly the height, of the material to be stored. It is not uncommon to have a range of goods with different requirements stored in the same storage space. For example a load for a large haulage trailer may have a section of the interior space used for goods which require the full height of the available space and another section for goods where there is room for two layers.
One solution to this problem is to install a removable second floor which can be stored out of the way when not required. Such floors are typically made in sections and stored near the ceiling of the storage space when not in use. When in use a section of the floor is lowered and locked into position to form a platform for further storage.
The use of a removable second floor can be illustrated by considering a truck or trailer unit having an enclosed canopy, termed a pan, fitted with a removable second floor which is located at the top of the pan when not in use. The material to be stored is taken to be in the form of loaded pallets although the same principles apply to other forms of storage.
The first step in loading the pan is to place a first row of pallets on the floor against the rear wall of the pan (ie the wall opposite the open end of the pan).
A first section of the second floor is then lowered and locked into position to form a support platform above the first row of loaded pallets. In this application the sections of the second floor are typically the same width as a pallet.
A forklift or other lifting device is then used to load a row of pallets onto the first section of the second floor.
This process is continued for each subsequent row until all the material is loaded or all the space on the floor of the pan and the second floor has been used.
Unloading is the reverse of this process whereby a forklift is used to remove the pallets from the section of the second floor closest to the open end of the pan. The unloaded section of the second floor is unlocked and moved into an out of use position, typically close to the ceiling. The row of pallets on the floor is then removed to allow access to the pallets on the next section of the second floor. The process is repeated until all pallets have been removed and the second floor stored in an out of use position.
Use of a second floor potentially enables double the load to be carried in the available space. However, there are a number of disadvantages with this method. In particular it requires use of a forklift (or other lifting device) in the interior of the pan to lift the pallets onto and off of the second floor. This means that a loading bay must be used in order for the forklift to access the interior of the truck both for loading and unloading. There are many situations where a loading dock is not available and therefore the second floor cannot be used.
Another disadvantage is the weight of the second floor adds to the overall tare weight of the vehicle. This could limit the weight of a load to be carried.
A variant on the removable floor solution involves the use of bearers configured to move up and down along fixed vertical tracks on each side of the storage space. In this situation a series of vertically oriented tracks are spaced along opposite sides of the storage space. A bearer can be moved up or down along the track to a position at the required height where it is locked against the track.
A support level can be achieved by moving a second neighbouring bearer along a second track and locking it at the same height. The two bearers can then be used to support a load that spans the horizontal separation of the two bearers. This could either be a large package or a loaded pallet.
This solution is essentially the same as the removable floor, except that support is provided by two or more bearers rather than a solid platform. It therefore suffers from the same disadvantages as the removable floor; in particular this arrangement requires use of a fork lift inside the storage area in order to load and unload the second support level.
Another solution to the problem of providing a second support level is the use of movable bearers. In this instance the upper support level within the storage space consists of a series of bearers, or beams, that span the space from one wall to the opposite wall of the storage space. The ends of the beams are connected to wheels or bearings which are supported by a track which runs horizontally along opposite sides of the storage space at the required height.
Loading of the storage space normally-begins with a first row of pallets being loaded onto the floor against the rear end of the space. A second row of pallets is loaded onto two or more movable bearers at the open end of the storage space. The loaded bearers are then moved into position over the first row of pallets and locked into position on the track. This process of placing a row on the floor followed by a row on the movable bearers above the row on the floor is repeated from the rear of the storage space towards the front until all pallets are loaded or the available space has been used.
The pallets can be loaded onto the movable bearers at the front or open end of the storage space either with the forklift on a raised platform, such as a docking bay, or at ground level. It is not necessary for the forklift to enter the interior of the storage area.
In practice the bearers of the movable bearer system are removed from the track as each row is unloaded, and placed back onto the track for each new load. This is because the bearers for the first row of pallets, being the row situated at the rear end of the storage space, need to be the first bearers on the track.
These first bearers are placed on the track and loaded with a row of pallets. The loaded bearers then pushed into position at the rear of the storage space before the bearers for the next row are loaded onto the track. The process is repeated with each set of loaded bearers being pushed into place before the next set of bearers is placed on the track.
Unloading is the reverse process whereby the pallets from the row closest to the open end of the storage space are removed first and those bearers removed from the rail. The row of pallets from the floor closest to the open end of the storage space is removed to enable access to the second row of pallets on the bearers. The loaded bearers are moved forward to the open end of the storage space where the pallets are removed, followed by removal of that set of bearers. This process is repeated until all the pallets and bearers are removed.
Considerable time and labour is required to remove and replace the bearers on the track as required. In addition, space must be found to store the bearers In instances where the space is to be used without the movable bearer system. Storing the bearers also requires additional time and labour.
The tracks used in the movable bearer systems described above are in the form of “L” shaped brackets attached to the side of the storage space. The wheel attached to the bearer runs along the horizontal section of the track. There is nothing in this basic arrangement to prevent the bearer from skewing sideways causing the wheel to leave the track, thus spilling any load from the bearer.
This problem is mitigated by the use of a wide horizontal section of the track onto which a cylindrical rod has been attached. The wheels attached to the beaters have a rim which is curved to fit over and around the upper surface of the cylindrical rod. The wheel moves along the cylindrical rod on the horizontal section of the track. This arrangement restricts the ability of the bearer to skew on the track.
However, with the bearers removed following unloading, the wide tracks protrude into the storage space to such an extent that they can limit the options for stacking a load when the bearer system is not in use.
This is also a problem when the space is being used for a mixed load where only part of the space is being used with the bearer system.
Furthermore, the horizontal ledge of the track which protrudes into the storage space presents a safety hazard for workers in the area.
For these reasons the track has to be removed and stored as well as the bearers whenever the bearer system is not in use.
On the occasions when the movable bearers are not required the bearers (and attached wheels) and the tracks are commonly stored outside of the storage area. In the case of a truck or trailer this is usually under the floor or tray of the truck or trailer.
The time and labour required to assemble the movable bearer system for use, and to disassemble and store it when not required is a major disadvantage with the system.
Thus there are significant disadvantages with both the removable second floor and the movable bearer system as means of providing additional support surfaces which limit the usefulness of both systems.
It is an object of the present invention to address the forgoing problems or at least to provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.